Chemical conversion and storage system for solar energy by use of catalytically active photogenerated hydride transients

有机金属配合物的光化学研究是当前的热点之一，具有配位不饱和性和高催化活性的短寿命有机金属配合物的光化学性质一直是人们研究的重点。我们曾报道过，亚膦酸二乙酯钴[Co-HL_4]（L=PPH（OEt）_2）的光催化反应中，一个配位的亚膦酸配体L解离，生成一个过渡态的钴（I）物种CoHL_3。包括烯烃的双键迁移和从仲醇到酮的氢转移。本文研究了亚膦酸钴配合物CoHL_4在Pyrex滤光光照射下催化异丙醇液相脱氢反应，并释放出丙酮。在82 ℃下脱氢1 h的转化数为4.6，在60和82 ℃下在366 nm处反应的量子产率被确定为约0.015。脱氢被表征为光助型催化反应，光生的过渡态CoHL_3是脱氢催化循环中起关键作用的中间体。

The photochemistry of organometallic complexes has been one of the currently active research-fields, and much effort has been focused on the properties of photogenerated short-lived organometallic fragments with coordinative unsaturation and high catalytic activities. We have reported that photoirtadiation of tetrakis (diethylphenylphosphonite) hydridocobalt (I) [Co-HL_4] (L=PPH (OEt)_2) gives a transient hydridocobalt (I) species "CoHL_3" with dissociation of one coordinated phosphonite ligand L.Catalytic activities of the photogenerated CoHL_3 species have been realized in many homogeneous reactions, involving double-bond migration of olefins and hydrogen transfer from secondary alcohols to ketones. The present study deals with photoassisted dehydrogenation of 2-propanol in the liquid phase with the hydrido (phosphonite) cobalt (I).The hydridocobalt (I) complex CoHL_4 under Pyrex-filtered photoirradiation catalyzed dehydrogenation reaction of 2-propanol in the liquid phase, with release of acetone. The turn-over number evaluated for the dehydrogenation for 1h at 82ﾟC was 4.6, and the quantum yields for the reaction at 366nm were determined to be about 0.015 at 60 and 82ﾟC.The dehydrogenation was characterized as a photoassisted-type catalytic reaction, and the photo generated hydrido transient CoHL_3 was attributed to a key-role-playing inter mediate in the catalytic cycle of the dehydrogenation.